 /*******************************************************************************
  * Copyright (c) 2005, 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.databinding.observable.masterdetail;

 import java.util.HashSet ;
 import java.util.Set ;

 import org.eclipse.core.databinding.observable.Diffs;
 import org.eclipse.core.databinding.observable.IObserving;
 import org.eclipse.core.databinding.observable.masterdetail.IObservableFactory;
 import org.eclipse.core.databinding.observable.set.IObservableSet;
 import org.eclipse.core.databinding.observable.set.ISetChangeListener;
 import org.eclipse.core.databinding.observable.set.ObservableSet;
 import org.eclipse.core.databinding.observable.set.SetChangeEvent;
 import org.eclipse.core.databinding.observable.value.IObservableValue;
 import org.eclipse.core.databinding.observable.value.IValueChangeListener;
 import org.eclipse.core.databinding.observable.value.ValueChangeEvent;
 import org.eclipse.core.runtime.Assert;

 /**
  * @since 3.2
  *
  */
 public class DetailObservableSet extends ObservableSet implements IObserving {

     private boolean updating = false;

     private ISetChangeListener innerChangeListener = new ISetChangeListener() {
         public void handleSetChange(SetChangeEvent event) {
             if (!updating) {
                 fireSetChange(event.diff);
             }
         }
     };

     private Object currentOuterValue;

     private IObservableSet innerObservableSet;

     private IObservableValue outerObservableValue;

     private IObservableFactory factory;

     /**
      * @param factory
      * @param outerObservableValue
      * @param detailType
      */
     public DetailObservableSet(IObservableFactory factory,
             IObservableValue outerObservableValue, Object detailType) {
         super(outerObservableValue.getRealm(), new HashSet (), detailType);
         this.factory = factory;
         this.outerObservableValue = outerObservableValue;
         updateInnerObservableValue(outerObservableValue);

         outerObservableValue.addValueChangeListener(outerChangeListener);
     }

     IValueChangeListener outerChangeListener = new IValueChangeListener() {
         public void handleValueChange(ValueChangeEvent event) {
             Set oldSet = new HashSet (wrappedSet);
             updateInnerObservableValue(outerObservableValue);
             fireSetChange(Diffs.computeSetDiff(oldSet, wrappedSet));
         }
     };

     private void updateInnerObservableValue(
             IObservableValue outerObservableValue) {
         currentOuterValue = outerObservableValue.getValue();
         if (innerObservableSet != null) {
             innerObservableSet.removeSetChangeListener(innerChangeListener);
             innerObservableSet.dispose();
         }
         if (currentOuterValue == null) {
             innerObservableSet = null;
             wrappedSet = new HashSet ();
         } else {
             this.innerObservableSet = (IObservableSet) factory
                     .createObservable(currentOuterValue);
             wrappedSet = innerObservableSet;

             if (elementType != null) {
                 Object innerValueType = innerObservableSet.getElementType();

                 Assert.isTrue(elementType.equals(innerValueType),
                         "Cannot change value type in a nested observable set"); //$NON-NLS-1$
 }

             innerObservableSet.addSetChangeListener(innerChangeListener);
         }
     }

     public void dispose() {
         super.dispose();

         if (outerObservableValue != null) {
             outerObservableValue.removeValueChangeListener(outerChangeListener);
             outerObservableValue.dispose();
         }
         if (innerObservableSet != null) {
             innerObservableSet.removeSetChangeListener(innerChangeListener);
             innerObservableSet.dispose();
         }
         currentOuterValue = null;
         factory = null;
         innerObservableSet = null;
         innerChangeListener = null;
     }

     public Object getObserved() {
         if (innerObservableSet instanceof IObserving) {
             return ((IObserving)innerObservableSet).getObserved();
         }
         return null;
     }

 }

